Here is my latest creation. I won't post all the details, please visit http://mocpages.com/moc.php/428357 in terms of how it works, details, etc. Briefly, I sought to create a funnycar that would propel itself. Because it would be propelling itself, it would have to be fairly large (enough air for short burst of speed), but at the same time light. limiting the coefficient of drag would also be very important. Thus the ungainly looks of the thing. But..... funnycars aren't built for looks, rather for acceleration... right? Kinda inspired by 42050....but I wanted to create something with an engine sound, fast, and help true to the funnycar name.

The drivetrain was incredibly simple but effective. Neutral… and one forward drive gear. This is the gear set-up for most drag racers. This can get complex though, with many sophisticated models allowing a type of clutch that limits slip and only allows a certain amount of torque to be applied at different RPM levels. But for all intents and purposes, for this model, all I wanted was neutral and drive. This certainly tested Lego gears, changeover catch, and drive rings. But incredibly, there was no skipping. This was quite amazing given the amount of torque that was applied to the drive train. This is similar to real drag racers. I remember a documentary I watched a while ago stating that the gears in a real drag racer only last 2-3 races before needing replacement because of the tremendous torque, heat, and stress applied.

The goal of the drive train was to have a neutral gear so that the engine (which is from lpepower.com, Thanks Alex! I love this engine!) could first rev up. Although the engine is quite powerful in and of itself, the fact that it was already running at approximately 1500 RPMs before the gears engaged really resulted in the car’s speed. The whole set-up looked like what is below. To explain the picture you have the arrows pointing in opposite directions representing the tendency of the drive ring to want to pop out of place because it was trying to engage a set of gears where moving at different speeds (well, one was moving and the other was stationary) and the rubber bands acting against it. Initially, when the engine was started I had an axle placed in the hole where the left arrow is to hold it in place. Placing the axle here would stretch the bands back and disengage the drive. So I would first start the engine, let it rev to approximately 1500 RPMs, put the axle, the bands would pull the catch, engage the drive ring into the receiving gear and….. we were off!

The “fuel” that was used was simply air. The air tank was the only thing in this model that was not 100% Lego. All else was. The setup was something that I had built before, just on a smaller scale (one liter bottle). Details can be found here but here are some photos. The 1 liter bottle I used I obviously blacked with spray paint.

Simply cut out the nozzle from a bike tube and used very strong epoxy-type glue to seal it all. Worked great.

Thanks for taking a look. Hope you enjoyed!

Edited May 2, 20168 yr by nerdsforprez

Awesome!

Did the car stop before it drove onto the street?

This is really something diferent!

And nice to see that engine put to work!

I dont know but this video was really fun to watch probably because of the awesome sound of the motor. Would it go faster if you stripped it of the body work and all unnecessary pieces?

First time I have seen Lego burning rubber! Funny and Amazing :D

Absolutely crazy, in the best possible way. A rubber burning monster!

Awesome!

Did the car stop before it drove onto the street?

Yes, it did. In fact, if you watch the video, in one of the frames you will see my my daughter out in the street (we make sure there are no cars, and it is a very safe, residential, street) anxiously awaiting to catch it. In fact, when the car peeled out it was the first time we had tried it at 60 PSI, and she gave a little "oh shoot!" because she was out of position that was caught in the audio pick up Pretty amazing that it would cover roughly 110 feet on only 1 liter of air (although once out of the garage, there is a very slight decline to the driveway).

I dont know but this video was really fun to watch probably because of the awesome sound of the motor. Would it go faster if you stripped it of the body work and all unnecessary pieces?

Probably...perhaps I should try it. The motor alone was 260ish grams. Whole model - 989 ish. Tires probably 50 a piece, and I would have to keep most of the frame and obviously the drive line. So I probably could not take much away, but I estimate all the flex cables, spoiler, scoop, and all other nonsense could be removed and save me perhaps 200-300 grams. Perhaps the most significant thing is that I could likely change the drive train to 1:1 with a 2-300 gram weight reduction.

Edited May 2, 20168 yr by nerdsforprez

Cool build.

So cool... :thumbup:

What speed did it reach?

Something very different, well done! :thumbup:

Awesome!

I am totaal agree with the comments above :thumbup:

Very cool creation.

Thanks everyone. Little different project. Tons of fun. Actually it began as a project for my daughters science fair..... But I took out a little further than that .....

I dont know but this video was really fun to watch probably because of the awesome sound of the motor. Would it go faster if you stripped it of the body work and all unnecessary pieces?

Okay.... so I couldn't help but give it a go without all the bodywork. I should have done like a picture in picture comparison but I lack the video software for that. Anyways, here is the vehicle stripped of anything that resembled bodywork. Decreased weight nearly 300 grams. So the model was just under 700 grams. Pretty light. I could then keep with the 1.6:1 gearing. Seems like it goes pretty fast..... faster than the other version. Which it should. Nearly 30% lighter.

Ive been curios as to how fast Lego cars can go then I saw this machine leaving rubber behind...totally awesome. The sound it makes is even better, had to watch it a few times in a row and still had a grin on my face. My hats off to you.

Wow! I love lpe vehicles. I want to make an lpe car/truck soon, an I was wondering how long did the bottle of air last at 50psi?

That video made me love LPE's even more like Epic Technic said. Who knew Lego could be so powerful.

Wow! I love lpe vehicles. I want to make an lpe car/truck soon, an I was wondering how long did the bottle of air last at 50psi?

I mentioned this earlier in the post. Pretty much just a few seconds at high power. Obviously it will drag on with little psi once the majority of the air is out. Essentially, this equated to the vehicle covering approximately 110 ft on the one liter. 60 psi it covered more.

So, really, for any other vehicle I don't think this set up would really work. But...... I have used larger air tanks for my unimog (below in signature block). Portable, very lightweight. Easy to make. For a truck or car, I think the set-up I used with my unimog would work much better. I got quite a bit of air out of that tank. Sure..... you have to tote it around.... but unless you are building an absolutely huge car/truck, an on-board air supply really is not feasible. For this vehicle on-board did work b/c I only needed a short burst of air.......

On that last 60psi run. Should have burnt out the tyres a bit beforehand for a bit more grip ☺☺ great fun little project I enjoyed watching the video.